The coronavirus case rate for unvaccinated people in Santa Clara County is roughly four times the rate for those who have been inoculated against the deadly virus.

According to the county’s new dashboard, the case rate — the total number of cases on a given day per 100,000 people — is 25.3 for unvaccinated residents and 6.8 for vaccinated residents.

With the highly transmissible delta variant spreading quickly throughout the Bay Area, the data shows an alarming rise in infections, especially among those who have not been. About a month ago, the case rate for unvaccinated people was hovering around 3. The figures also show a spike in cases among the county’s vaccinated residents, up from a case rate of around 1 at the start of July, a troubling trajectory that has led to new vaccine requirements by many employers and universal mask mandates indoors.

More than 1.3 million people in the county are fully vaccinated, with another nearly 103,000 residents partially vaccinated. Vaccinations in California also appear to be on the rise, up 54% since a low in early July.

“Vaccines are still excellent at protecting against serious illness and death. They also provide significant protection against infection, though perhaps not quite as effective against the delta variant,” George Han, the county’s deputy health officer, said in a statement.

Nearly 80% of Santa Clara County residents 12 and up are fully vaccinated, one of the highest rates in the country. But officials are trying to boost vaccination rates in a bid to protect those who can’t yet get their shots, including young children returning to classrooms for the new school year.

The county said it is working on assembling similar data for hospitalizations and deaths, but that approximately eight or nine out of every 10 COVID-19 hospitalizations involve unvaccinated people, with almost everyone infected with the delta variant.

Santa Clara County joins several other counties, including Marin and Contra Costa, in publishing case rates by vaccination status. In Marin County, the case rate for unvaccinated residents (36.6) is roughly four times the rate for vaccinated residents (9.2). And in Contra Costa County, the case rate for unvaccinated residents (60.7) at the end of July was more than five times as high as for vaccinated residents (10.7).

The California Department of Public Health did not immediately respond to a request for comment about whether it also plans to publish statewide case rates by vaccination status.

“To protect those who are not yet eligible for vaccination, such as children, and people who are elderly or immunocompromised, we need everyone who can get a vaccine to do so now,” Han said. “Additionally, wearing masks indoors will help minimize the spike in community transmission.”